This research is directed towards the fluorescent imaging and excited state lifetime measurement of single hexameric protein, r phycoerythrin (R-PE), using near field and far field microscopic techniques developed at the RLBL. The goal is to evaluate the aggregation state of single R-PE molecules and directly correlate it to energy transfer in protein subunits and monomeric forms. R-PE exhibits near unit fluorescence quantum yields and is photostable.